How are you making a rectangular frame but it needs to be a triangle?
The pricing of the boxes seems to be consistently 2.40 per box. Ethan's cost is
.. 52.80 = 2.40 * (# of boxes)
.. 52.80/2.40 = (# of boxes)
.. 22 = # of boxes
Ethan has bought 22 boxes for 52.80.
1/2-1/4
(1/2x2)-1/4
2/4-1/4
2-1
1
1/4
Explanation
We must the tangent line at x = 3 of the function:

The tangent line is given by:

Where:
• m is the slope of the tangent line of f(x) at x = h,
,
• k = f(h) is the value of the function at x = h.
In this case, we have h = 3.
1) First, we compute the derivative of f(x):

2) By evaluating the result of f'(x) at x = h = 3, we get:

3) The value of k is:

4) Replacing the values of m, h and k in the general equation of the tangent line, we get:

Plotting the function f(x) and the tangent line we verify that our result is correct:
Answer
The equation of the tangent line to f(x) and x = 3 is: